Duty Cycle 1980 slc

[450slcguy]

I've been reading alot of posts on the duty cycle but most appear to be for 1985 and later cars. My 1980 was the first year for lambda system.

I purchased a Sears dmm with duty cycle. The CD say's connect "voltmeter" with black lead to pin 3 and red to 12 volt source.

Most of the posts I've read say to connect red to pin 3 and black to pin 2. This is the way I proceeded, and couldn't get the % any lower than 632 before stalling.

On an early model 107's using a duty cycle dmm which way should I connect the red/black leads? Black on pin 2 / red on 12v, or red on pin 2 black on pin 3?

[mbdoc]

That car & all V-8' upto 1986 don't use a standard duty cycle signal.

That signal from the computer is actually a Hz frequency. We used a special "LAMDA" box to set-up that fuel mixture.

You can measure the O2 voltage & set the mixture by splitting that signal into half's.

[450slcguy]

Originally Posted by M.B.DOC

That car & all V-8' upto 1986 don't use a standard duty cycle signal.

That signal from the computer is actually a Hz frequency. We used a special "LAMDA" box to set-up that fuel mixture.

You can measure the O2 voltage & set the mixture by splitting that signal into half's.

From where can I measure that voltage? Can i measue it from the diagnostic socket pin 3? Thanks

[mbdoc]

Needs to be measured at the O2 sensor OR at the computer. Measure dynamically, with the system operating in closed loop.